Question for the Europeans about new washers with both hot and cold water intakes

[toggleswitch2]

I never understood the aversion to simply replacing the storage tank with a modern one and including a temperature-pressure relief value. This way water-storing cisterns are avoided and regular mains pressure can be what is used to move the heated water.

 

[MrX]

Pumped shower (Ireland)

Here's a typical 'power shower' setup.

 

[MrX]

With the pump !

The above is the standard system.

With a pump added it looks like this :

 

[mielabor]

What are the advantages of a gravity fed hot water system? It looks rather complicated to me. Here in the Netherlands I have never seen such an installation.

 

[dj-gabriele]

In Italy too, I've never heard of something like that, hot water is connected to the main line and has the same pressure as cold water. This way, with no added pressure, doesn't it take longer to fill a tub or other water intensive talks? I know that when my water pressure is under 2,5 bars (36,3 psi) it takes 20 minutes to fill the tub, compared to the 10 or so when the pressure is normal.

 

[MrX]

The main reason for the gravity fed system is that the attic tank acts as a buffer between the water mains and the house. The idea originated back when early 'modern' domestic water systems started to arrive in the 1800s.

During times of peak demand, it prevents a pressure drop on the public water mains, as the head-tank in the attic of each building provides sufficient water for baths and showers, and allows the public mains to 'catch up'.

The system's design originates from a time when hot water systems were not thermostatically controlled, and were often heated by a back boiler in a range or a fire.

Rather than relying on emergency relief valves, the system is pressurised by the header tank, and is effectively open. Should the system over heat, steam can escape through the pipe marked '3'.

It also tends to keep plumbing a little healthier as it's not exposed to the extreme pressures of the public system. Where shower booster pumps are installed, they only operate when the water is flowing, and stop once the taps are closed. So, they exert very little extra pressure on the system. The 'static pressure' (when no water is flowing) is the same as a non-pumped system.

The British and Irish plumbing rules also seem to have had a serious focus on ensuring that water mains could not be contaminated with 'dirty water' re-entering from taps in the event of a sudden loss of system pressure / a fault.

Hence, the header tank avoided connecting toilets, baths and bathroom sinks directly to the water mains. It also prevented any risk of hot water flowing back into the public system.

Even today, some local authorities and water companies are quite strongly opposed to the idea of directly connecting pressure washers, or any 'devices' to the water mains, even with a non-return valve. They are a bit fixated on the concept that if a pressure washer were to suck more water out of the mains than it could supply, it could contaminate the line.

So, in theory you're supposed to use a buffer tank between the pressure washer and the mains!

Having the gravity fed system does make it possible to have a pumped power shower. So, you can enjoy pressures of 6 bars+ in the shower if you really like the fire hose effect!

Nothing about British-influenced domestic wiring or plumbing is straight forward! You don't seriously expect us 'weird islanders' to use 'continental' or worse still, American standards now do you ? hehe

 

[favorit]

storage / gravity fed sys

Similar systems are used in in some parts of Southern Italy, where draught has always been an issue. Sometimes people living there have water pressure in public pipelines only for few hours a day (typically by night), so they store water for the next day(s).

Anyway this is mostly a problem of past times.
For their luck (?!?) in the last 4/5 years they have had a lot of rain (often too much ---> floods).
Last winter in Sicily they have even had snow on the seaside (not so rare in Venice .... a unique event in Palermo !)

 

[brisnat81]

Gravity Electric and Wood Fired (Through a range loop) storage tanks were commonly installed here up until the 70s. After that, pretty much has been mains pressure hotwater.

Cold water was always at mains pressure here, you just had a ball cock on top of the tank that kept it full and an element in the bottom that heated for x number of hours per day. These tanks were much larger than the pressure tanks, around 800L at the biggest size here, whereas the biggest pressure tank is about 400L.

My grandparents recently replaced the gravity tank with a solar tank and panels, and for the first time ever they have hotwater that runs at more than a very slow flow and almost at the same rate as the cold water.

 

[MrX]

That's the typical hot water cylinder here

Here's the layout of a typical hotwater cylinder here.

 

[favorit]

mine is like this

just hasn't the electric heater (6) but two heat exchangers/coils like the one (5) in the pic

One coil is powered with water coming from the Vaillant flow-through gas heater. The some gas heater feeds radiators via another heath exchanger (when needed)

The other coil works by solar panels. When solar has enough power, the gas heater doesn't work at all

Even we're gone a bit OT ... this is very interesting

 

[toggleswitch2]

Thanks mrx, I knew you'd shed some good light as to theory behind actions!

Very tall apartment buildings in Manhattan ["downtown" or "central"] New York City have large woodens cisterns on their roofs for water storage. City pressure alone can't get the water up much past 6 stories => (storys U.K.) at any type of decent pressure. So these are filled with a pump/booster and feed BOTH HOT AND COLD in the building by gravity.

http://www.nydailynews.com/money/2008/05/05/2008-05-05_142yearold_rosenwach_tank_makes_icons_of.html

 

[toggleswitch2]

More about wooden water-storing cisterns.